Recently, the number of patients suffering from bone maladies such as osteoporosis, fracture and lumbago is increasing in proportion to increase of aged people. These bone maladies are mainly caused by lack of calcium intake, lowering of calcium absorbing ability, lack of secretion of active vitamin D.sub.3, unbalance of hormones relating calcium metabolism and the like and the main causes are made clear as follows.
In bone tissues, bones are always destroyed, resorbed and created. At young ages, the bone resorption and formation are balanced, but the bone resorbing activity in the bone tissues becomes higher than the bone creating activity in proportion to aging (hereinafter called uncoupling) by various causes. When the uncoupling continues for a long time, the bone tissues become brittle and the above mentioned maladies are caused. Therefore, it is considered that the osteoporosis, fracture and lumbago can be prevented by preventing the uncoupling.
As treatments and prevention against the maladies in joints of bones and osteoporosis by preventing the uncoupling, (1) sufficient calcium supply by foods, (2) light exercises, (3) sun tan and (4) medical treatments have been performed in past.
For the calcium supply by foods, calcium salts such as calcium carbonate, calcium lactate, calcium phosphate and the like and natural calcium materials such as bovine bone powder, egg shell powder, fish bone powder and the like are used. However, some of these calcium salts become water insoluble in digestive organs and cannot be absorbed from intestines and absorbed calcium is not always used for bone formation, if bone creating activities are low.
For the light exercises, a light walk for around 30 minutes or the like is considered to be recommendable. However, as a body becomes weak, it becomes hard to do light exercises. Furthermore, it is almost impossible to do exercises for aged people who cannot even get up from a bed.
Sunlight promotes the biosynthesis of vitamin D.sub.3 in the human body, but the supply of vitamin D.sub.3 is not enough to prevent the uncoupling and to prevent maladies in joints of bones and osteoporosis.
For the medical treatments, medicines such as 1.alpha.-hydroxyvitamin D.sub.3, calcitonin and the like are popularly known for bone enhancing ability themselves. However, these medicines consist of chemical compounds as effective components and are not food materials which can enhance bones by being taken safely in a mild condition for a long time.
As mentioned above, the food materials taken safely in a mild condition for a long time to enhance bones, whose effect is proved and established, are not known yet.